The present invention relates to a method for continuously manufacturing an optical article having the large impact strength in which a polarizer is incorporated, particularly, a method for continuously manufacturing an optical lens, for example, a lens used for goggles, or sunglasses with or without degree having the large impact strength.
Goggles and glasses which are used in sports fields such as skiing, snowboarding, ice skating, sailing, boating, biking and motorcycling, and in industrial fields such as an architectural and civil engineering industry, a chemical industry and a machine manufacturing industry are used for the purpose of prevention of dazzling due to the direct or reflected light and protection of eyes from a wind, a snowflake, a rain, seawater, water, sands, a chemical agent or a foreign body. In addition, as a general use, sunglasses with or without degree are used for the purpose of prevention of dazzling due to the ray or the reflected light.
Hitherto, there have been manufacturing techniques of a polarizing glass lens in which both sides of a polarizer sheet are covered with a glass, and of a polarizing plastic lens, for example, polarizing CR-39 lens, manufactured by inserting a polarizer sheet into a mold followed by cast-molding.
In addition, there has been known a method for manufacturing an optical molded composite by an insert injection-molding method in which a polarizing plate having a laminate structure holding a polarizer sheet between two polycarbonate sheets is inserted into a mold, and then a polycarbonate resin layer is thermally adhered to the polycarbonate sheet portion on either side of the polarizing plate (Japanese Unexamined Patent Publication No. 245259/1999).
However, the polarizing glass lens in which both sides of the polarizer sheet are covered with a glass as described above has defects of easily fractorable property due to a glass base, and of poor processability due to small deformability of a base.
In addition, in the polarizing plastic lens manufactured by an insert cast-molding method in which a polarizer sheet is inserted into a mold and cast-molded has problems that a technique for incorporating a polarizer sheet into a mold is required, and that polarizing performance of the lens is lowered because the polarizer sheet is shrunk or thermally degraded due to the heat receiving for a long time during cast-molding.
In addition, all of the methods as described above, including a method for manufacturing an optical molded composite by an insert injection-molding method in which a polycarbonate resin layer is thermally adhered to an outermost polycarbonate sheet of a polarizing plate shown in Japanese Unexamined Patent Publication No. 245259/1999, are basically methods of hand-making lenses by one by one and, therefore, have a problem that the steps are interrupted several times between attaching, cutting and molding of the sheet during working. Such the interruption of the steps becomes a cause of forcing up the manufacturing cost due to an increase in required hands, contamination of an impurity accompanying with transfer of the sheet between the steps, lowering of a yield, and the like.
In addition, although the polarizer sheet is generally supplied in a state that a protective sheet is attached thereto, it is necessary to peel a protective sheet one by one upon covering of the polarizer sheet with a glass, or upon insert cast-molding or insert injection-molding. Since it is difficult to diselectrify static electricity during a step of separately peeling the protective sheet and a transference step thereafter, dust adsorption due to the static electricity is easily caused, and this may lead to a cause of an impurity defect of the final product.
In order to solve the technical problems as described above, the present invention provides (1) a method for continuously manufacturing an optical article which comprises a first step of thermal press-molding a sheet-like curved body and a second step of insert-molding a back resin on a concave side of the sheet-like curved body, while transferring a continuous sheet in a longitudinal direction, using an apparatus for manufacturing an optical article in which a press-molding machine which can thermal press-mold the sheet-like curved body and an insert injection-molding machine equipped with a mold having a curvature similar to that of the sheet-like curved body are serially positioned in this order, wherein a cycle of thermal press-molding and a cycle of insert injection-molding are synchronized to continuously insert injection-mold the back resin on a concave side of the sheet-like curved body while continuously thermal press-molding the sheet-like curved body.
In addition, the present invention provides (2) the method according to (1) as described above, wherein the continuous sheet is a multi-layered sheet comprising two or more layers of sheets containing one layer of a polarizer sheet.
In addition, the present invention provides (3) the method according to (2) as described above, wherein outermost attaching sheets of the continuous sheet other than the polarizer sheet are attaching sheets of acylcellulose, polycarbonate, polyamide, polyester, or a hydrocarbon-series resin having a main chain containing at least one selected from an adamantane ring residue, a norbornene ring residue and a cyclopentane ring residue.
In addition, the present invention provides (4) the method according to (2) or (3) as described above, wherein a sheet on the side of the continuous sheet on which the back resin is insert injection-molded is an attaching sheet of polycarbonate, polyamide, polyester, or a hydrocarbon-series resin having a main chain containing at least one selected from an adamantane ring residue, a norbornene ring residue and a cyclopentane ring residue.
In addition, the present invention provides (5) the method according to any one of (1)-(4) as described above, wherein the back resin is polycarbonate, polyamide, polyester, or a hydrocarbon-series resin having a main chain containing at least one selected from an adamantane ring residue, a norbornene ring residue and a cyclopentane ring residue, and is thermally adherable with the sheet-like curved body.
In addition, the present invention provides (6) the method according to any one of (1)-(5) as described above, wherein the thermal press-molding machine comprises a planar support which has a hole having a size similar to that of the sheet-like curved body, a ring clamp which concentrically secures the continuous sheet on the support around the hole, and an anvil having a size and a curvature corresponding to those of the sheet-like curved body, wherein the anvil has a structure fittable in the support, and wherein the step of thermal press-molding the continuous sheet into the sheet-like curved body comprises a cycle of stopping the feed of the continuous sheetxe2x80x94securing the continuous sheet on the support by the ring clampxe2x80x94fitting the heated anvil in the hole of the support and thermal press-moldingxe2x80x94returning the anvil and ring clamp to the original positionsxe2x80x94feeding the continuous sheet as one cycle.
In addition, the present invention provides (7) the method according to any one of(1)-(6) as described above, wherein the insert injection-molding machine comprises a front mold having a curvature similar to that of the sheet-like curved body and having a suction hole for adhering thereto the sheet-like curved body by suction and a movable mold having an optional curvature, and wherein the step of insert injection-molding the optical article comprises a cycle of stopping the feed of the continuous sheet on which the sheet-like curved body is thermal press-molded-inserting the sheet-like curved body into the front mold-securing the sheet-like curved body to the front mold by suction-clamping the movable mold to the front mold-injection-molding the back resin-removing the optical article-feeding the continuous sheet as one cycle.
In addition, the present invention provides the method according to any one of (1)-(7) as described above, wherein the optical article is an optical lens.